ACOUSTIC TRANSFORMER

A device, such as a horn or megaphone, for increasing the efficiency of sound radiation.


Related Terms

DISTORTION

  1. Any undesired change in the waveform of an electric signal passing through a circuit or other transmission medium.
  2. In general, the extent to which a system fails to accurately reproduce the characteristics of an input signal at its output.
  3. Any undesired change in the waveform of a sound wave.

DIRECTIVITY FACTOR

  1. The ratio of radiated sound intensity at a remote point on the principal axis of a loudspeaker or other transducer, to the average intensity of the sound transmitted through a sphere passing through the remote point and concentric with the transducer; the frequency must be stated.
  2. The ratio of the square of the voltage produced by sound waves arriving parallel to the principal axis of a microphone or other receiving transducer, to the mean square of the voltage that would be produced if sound waves having the same frequency and mean-square pressure were arriving simultaneously from all directions with random phase; the frequency must be stated.

POLAR RADIATION PATTERN

[ENG ACOUS] Diagram showing the strength of sound waves radiated from a loudspeaker in various directions in a sections or lengths to oppose one another.

PARABOLOID

A reflecting surface which is a paraboloid of revolution and is used as a reflector for sound waves and microwave radiation.

PARABOLIC MICROPHONE

[ENG ACOUS] A microphone used at the focal point of a parabolic sound reflector to give improved sensitivity and directivity, as required for picking up a band marching down a football field.

OMNIDIRECTIONAL HYDROPHONE

[ENG ACOUS] A hydrophone whose response is fundamentally independent of the incident sound wave's angle of arrival.

NOISE REDUCTION

[ENG ACOUS] A process whereby the average transmission of the sound track of a motion picture print, averaged across the track, is decreased for signals of low level; since background noise introduced by the sound track is less at low transmission, this process reduces noise during soft passages.

MONOPHONIC SOUND

[ENG ACOUS] Sound produced by a system in which one or more microphones feed a single transducing channel which is coupled to one or more loudspeakers.

MONAURAL SOUND

[ENG ACOUS] Sound produced by a system in which one or more microphones are connected to a single transducing channel which is coupled to one or two earphones worn by the listener.

MICROPHONE

[ENG ACOUS] An electroacoustic device containing a transducer which is actuated by sound waves and delivers essentially equivalent electric waves.

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